Element for immunoassay and process of using the same

Abstract

A dipping element for immunoassay or quantitative analysis of an immunoreactive analyte is disclosed having a first matrix having a carrier therein containing an immobilized antibody capable of an immunochemical reaction with a sample antigen. The immobilized antibody is not released into the aqueous liquid sample upon contact. The element further comprises a second matrix which contains labelled antigen which does dissolve in the aqueous liquid sample upon contact. On dipping, the marker-labelled antigen reacts with the immobilized antibody in competition with the antigen-antibody reaction between the analyte antigen and the immobilized antibody. if the analyte is an antibody, then the second matrix contains a marker labelled antibody and the first matrix contains an immobilized antigen. Methods for the quantitative analysis of an analyte antigen or antibody are also disclosed.

What is claimed is: 
     
       1. A process for the quantitative analysis of a sample antigen contained in an aqueous liquid sample wherein said sample antigen reacts with an immobilized antibody in competition with an antigen labelled with a marker in an antigen-immobilized antibody reaction, and wherein the quantity of said labelled antigen which has not combined with the immobilized antibody and which is a function of the concentration of said sample antigen is determined, comprising the steps of: (a) immersing a dipstick analytical element into the aqueous liquid sample, said element comprising:   a first matrix,   a carrier in said first matrix containing immobilized antibody capable of immunochemical reaction with sample antigen wherein the immobilized antibody is not released into the aqueous liquid sample upon immersion therein; and, a second matrix containing labelled antigen and a hydrophilic polymer binder wherein the labelled antigen and the hydrophilic polymer binder dissolve in the aqueous liquid sample upon immersion therein to release said labelled antigen into said aqueous liquid sample;   whereby said labelled antigen reacts with said immobilized antibody in competition with said sample antigen in the antigen-immobilized antibody reaction between said sample antigen and said immobilized antibody, so that only that portion of the labelled antigen which has not combined with said immobilized antibody remains in said aqueous liquid sample; and   (b) applying an aliquot of said aqueous liquid sample resulting from step (a) to a separate analytical element to determine the quantity of labelled antigen remaining in said aqueous liquid sample after the competition of the competitive antigen-immobilized antibody reactions and determining the amount of the sample antigen.   
     
     
       2. The process of claim 1 wherein said second matrix is composed of a filter paper containing the labelled antigen and a hydrophilic polymer binder. 
     
     
       3. A process for the quantitative analysis of a sample antibody contained in an aqueous liquid sample wherein said sample antibody reacts with an immobilized antigen in competition with an antibody labelled with a marker in an antibody-immobilized antigen reaction, and wherein the quantity of said labelled antibody which has not combined with the immobilized antigen and which is a function of the concentration of said sample antibody is determined, comprising the steps of; (a) immersing a dipstick analytical element into the aqueous liquid sample, said element comprising:   a first matrix,   a carrier in said first matrix containing immobilized antigen capable of immunochemical reaction with sample antibody wherein the immobilized antigen is not released into the aqueous liquid sample upon immersion therein; and, a second matrix containing labelled antibody and a hydrophilic polymer binder wherein the labelled antibody and the hydrophilic polymer binder dissolve in the aqueous liquid sample upon immersion therein to release said labelled antibody into said aqueous liquid sample;   wherein said labelled antibody reacts with said immobilized antigen in competition with said sample antibody in the antibody-antigen reaction between said sample antibody and said immobilized antigen,   so that only that portion of the labelled antibody which has not combined with said immobilized antibody remains in said aqueous liquid sample; and   (b) applying an aliquot of said aqueous liquid sample resulting from step (a) to a separate analytical element to determine the quantity of labelled antibody remaining in said aqueous liquid sample after the completion of the competitive antibody immobilized antigen reactions.   
     
     
       4. The process of claim 3 wherein said second matrix is composed of a filter paper containing the labelled antibody and a hydrophilic polymer binder.